Abstract We exposed a stack of polyethylene terephthalate (PET) detectors each of thickness 100 μ m with an area of 21 cm × 30 cm along with a separate stack of the standard solid state nuclear track detector (SSNTD) CR-39 (Intercast Europe Co., Italy) of thickness 630 μ m and area 20 cm × 24 cm at Darjeeling, India in the Eastern Himalayan Range, under an atmospheric pressure of 765 hPa. The SSNTDs were kept horizontally in the open air for ∼ 1.5 × 10 7 s . After etching the PET detectors in 6.25 N NaOH solution at 55 ± 0 . 1 ∘ C , and partial scanning, it is found that the PET detectors recorded 188 particle tracks of near normal incidence within an area ∼ 0.37 cm 2 . The observed flux being ∼ 10 - 5 / ( cm 2 s sr ) we have tried to explain our observation on PET detector vis-à-vis the tracks recorded in CR39 exposed simultaneously under similar conditions.